Jared Spool points out that consistency is a matter of dealing with user’s current knowledge – not with formal elements of the visual design. Unfortunatly he uses a very misleading headline for is article which is really not in line with the point he is trying to make. The headline is »Consistency in Design is the Wrong Approach« and he writes:
The problem with thinking in terms of consistency is that those thoughts focus purely on the design and the user can get lost. “Is what I’m designing consistent with other things we’ve designed (or others have designed)?” is the wrong question to ask.
Instead, the right question is, “Will the user’s current knowledge help them understand how to use what I’m designing?” Current knowledge is the knowledge the user has when they approach the design. It’s the sum of all their previous experiences with relevant products and designs.
And then he proposes to focus on current knowledge of a user during the design process and concludes:
Funny thing about thinking about current knowledge: when you’re done, your interface will feel consistent.
Wait! What was the headline saying? Wasn’t it talking about consistency being a wrong approach? He continues:
My recommendation: anytime someone on your team starts talking about making things consistent, change the conversation to be about what the users’ current knowledge is.
Well, finally what Mr. Spool is saying in his article is just that consistency is not a question of form, but rather question of cognition. But maybe a headline like »Consistency is about cognition and not form« wouldn’t have been “news” enough to attract readers. To spin headlines into something more flashy that will potentially catch the eye when it appears in a list of news items is a common practice among web authors. I’d say the message in the headline should be consistent with the message of the article to really allow users to decide if it is worth click (or an actual read) or not.
Anyway, the problem with current knowledge is, that it might not be the right question at all to solve the cognitive problem, because current knowledge is hypotetical most of the time or a statistical measure at best. So after two team members bang their heads about »consistency vs. current knowledge« you might consider to change the conversation to »learnability« (e.g. asking how »user’s current knowledge« actually could be established and how users understand new things instead of speculating there is something they already have understood). And suddenly you are looping back to formal consistency, because learnability also is a question of reinforcing things through similarity and repetition – especially if the signs used are kind of arbitrary (which is more often the case than necessary I admit).
So I think the conclusion suggesting that current knowledge is a better way to think about the cognitive issue is not a good way to address the problem. It is just one way to think about the problem (among two or three valid others).
I fully agree with Jared Spool in this: The idea of formal consistency can lead to a mindset that shortens out the conceptual implications. The constrain to just formal variables has become a bad habit. It’s like you can see that people talk about »look & feel« while actually just talking about »look« and not »feel«.
The article by Jared Spool has been linked by elearningpost and GUUUI.com.